Kicker L5 15" enclosure

Hey I need some help with an enclosure. I have installed 2 Kicker L5 15's in the hatch of a 88 IROC-Z. They are facing straight up in a 3 cu.ft sealed box. I am pushing them with a Audiobahn A2200HCX. This amp is 1600w x 1 rms @1 ohm. My problem is that the subs dont play the upper frequencys worth a crap. The lows are crazy, but this limits the musical ability. Does anybody have experience with these subs? Should my box be a  little bigger?. The Kicker manual says 1.5-6.0 cu. ft. That makes it hard to get it right. I want bass that makes your hair stand up, but still want to be able to feel like i'm front row at a AC/DC concert. If it helps I have a Pioneer DEH7500 head unit, a Audiobahn  line driver, a Audiobahn 2150 amp,(inside speakers) and Audiobahn 4x6's and 6x9's. Thanks for the help!

The 15's are designed for the big bad bottom end, not the upper frequencies. A 10" sub can play the same lows as a 15", just not with the same authority but they do a much better job at producing the upper frequencies. By making the box a little bigger you will actually increase the bottom end capabilities and lower the power handling of the speakers. You best bet might be a pair of 10" drivers in a sealed box and bandpassed to run between approx 70-120hz, this means another amp and a crossover that has bandpass capabilites.

-------------
Top Secret, I can tell you but then my wife will kill me.

So is there no way to make them more musical? I had 2 Orion XTR Pro 15's on a Rockford Power 800 and they pounded like crazy....and you could listen to everyday music on them as well. I was hoping that a bigger box would help eliminate this problem. Thanks so much for the info.

The Kicker L5's and L7's are simply not designed for high-frequency bass, instead they're made for that "crazy low-end".  About the only thing you can do with them is either make a vented or band-pass box with a high target fq or better yet, get some mid-bass speakers.